Rectorite

Glass transition temperature (Tg) for pure NR is —63.43°C, while for the nanocomposite it increases to —61.92°C. NR-rectorite nanocomposite shows a higher glass transition temperature, lower tan 8 peak, and slightly broader glass transition region compared to pure NR. 

Ca and Mg is inversed for vermiculite and montmorillonite (Levy and Shainberg, 1972). Further, the natural mica-beidellite interlayered minerals (rectorite) are sodi-calcic while the mica-montmorillonite minerals (allevardite) are sodi-potassic. Quite possibly, the site of charge imbalance changes the selectivity coefficients for exchangeable ions. The montmorillonite series of interlayering will produce illite and the beidel-litic series could lead to a paragonitic or possibly calcic mica. 

Martin Vivaldi and MacEwan, 1960) is a rough equivalent of rectorite or allevardite-like minerals. However, corrensite is less frequent in sedimentary rocks and sediments than the dioctahedral mixed layered minerals. It is possible that corrensite has been overlooked and is more common in argillaceous rocks than so far reported. It is nevertheless evident that corrensite occurs in a variety of geologic environments. 

Chemical analyses and structural formulas of rectorite-like clays... 

Cole (1966) rectorite-like clay formed from weathered feldspar, Surges Bay, Tasmania. 

Detailed Fourier transform studies indicate some of these long-spacing (25 A-30 A) clays are not ideally regular. A sample (No.5) described by Cole (1966) contains 72% rectorite-like layers (AB), 18% single mica layers (A), and 10% double mica layers (AA) for an average of 64% mica layers and 36% expandable layers. 

Bradley, W.F., 1950. The alternating layer sequence of rectorite. Am. Mineralogist, 35 590-595. 

Rateyev, M.A., Gradusov, B.P. and Kheirov, M.B., 1969. Potassium rectorite from the Upper Carboniferous of the Samarskaya Luka (Samara Bend of the Volga). Dokl. Akad. Nauk S.S.S.R., 185 116-119. 

The other clay mineral, illite, also has some strontium sorption, but the distribution coefficient is about one order of magnitude lower than that of montmorillonite and rectorite. Since, in illite, the layer charge is compensated by non-exchangeable cations (Chapter 1, Table 1.2), cation sorption can takes place only on the deprotonated edge sites. This is the case for tectosilicates (quartz, cristobalite). 

The clay minerals used in this study differ from the rectorite used by Jie et al. (3) in that the negative charge of the clay layers is due, primarily, to isomorphous substitutions in the octahedral layers while the corresponding charge in the rectorite is caused by substitutions in the tetrahedral layers. 

At this point, the most promising types of pillared clays for use as cracking catalysts are the pillared rectorite developed by Jie et al. (3) and the large pore Ce/Al-pillared smectites developed by McCauley W. Further studies will have to be performed in order to determine the feasibility of these to types of materials for this application. 

Hitherto the most successful pillaring has been carried out on smectite type clays. The original research on pillaring included several series of unsuccessful experiments on mica, vermiculite and the sheet silicic acid minerals magadiite, silhydrite and kenyaite. Recently renewed attention has focused on these and other alternative sheet structures. They include rectorite, zirconium phosphates, tetrasilicic micas, hydrotalcites and silicic acids, the general structural features of which are shown in Figure 4. 

Rectorite is one of an almost infinite number of randomly mixed layer clays (411. collectively called illites, which include several other ordered interstratified varieties, including chlorite, corrensite and allevardite. Rectorite has the advantages of a mica and a smectite, in that alternate interlayers are expanding and non-expanding. It may be viewed as an ordered synthetic mica-montmorillonite (SMM) in the nomenclature familiar to catalytic... 

The tetrasilicic micas (TSM) are synthetic expandable fluoromicas (50) recently made available by Topy Industries (Japan) (51). They can be effectively pillared (52). and show interesting catalytic activity and enhanced stability, although not at the level of the rectorite-PILC. The chemical and physical properties of this group of materials do not yet seem to have been optimized, and probably require more extensive synthesis work before the full potential of TSM can be realized in pillared systems. 

Figure 5. A comparison of catalytic activities using a light cycle oil over deactivated catalysts based on pillared montmorillonite, pillared rectorite, NaY and an amorphous silica-alumina FCC.

Laver Smectites Rectorite Tetrasilicic Mica Smectites Smectites Smectites... 

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